I definitely relate to the bikeshedding thing. I like what someone from Nintendo once said.
"You're making a game. The engine is what's leftover when you're done."
I like to think that way as well.
Sure, I have a laundry list of things to do, but it all starts with a gameplay idea that I want to explore. I force myself to justify all development efforts by way of serving the gameplay ideas.
That way, you're making a game first and foremost and the "engine" is the tool you make to make the game.
"You're making a game. The engine is what's leftover when you're done."
I like to think that way as well.
Sure, I have a laundry list of things to do, but it all starts with a gameplay idea that I want to explore. I force myself to justify all development efforts by way of serving the gameplay ideas.
That way, you're making a game first and foremost and the "engine" is the tool you make to make the game.